The present invention relates generally to a laryngoscope, and more particularly to a laryngoscope including a mechanism to selectively lock the blade to the handle in an operative position.
The use of a laryngoscope for the intubation of a patient, as well as its use in other procedures, is well known in the art. FIG. 1 illustrates a typical prior art laryngoscope, generally indicated by reference numeral 10, in use during a representative procedure. Laryngoscope 10 includes a handle 12 and a blade 14. The blade includes a handle connecting segment 16 and a tongue engaging segment 18 inserted into a patient 20, as shown in FIG. 1. The laryngoscope of FIG. 1 also includes fiber optic viewing means 22 for remote viewing of the anatomy of the patient adjacent tongue engaging segment 18.
FIG. 2, which is taken directly from U.S. Pat. No. 4,437,458, specifically shows details of the prior art arrangement of FIG. 1 relating to the connection of blade 14 to handle 12. The handle includes a crossbar pin 24 extending between a pair of parallel upright structures 26, only one of which is shown. Crossbar pin 24 is engaged by a slot 28 on handle connecting segment 16 of the blade. The crossbar pin is resiliently held to the blade by a detent 29 which is also typical in the prior art. The blade is pivotally movable about pin 24 between an inoperative position in which tongue engaging segment 18 may be moved to a position directly adjacent handle 12 (not shown) and an operative position (as depicted in FIGS. 1 and 2) in which the blade extends forward from the handle.
Referring again to FIG. 2, the blade is held in the operative position by a pair of opposing locking mechanisms 30, carried by opposing sides of the handle connecting segments of blade 14. In prior art assemblies, typical of the one illustrated here, the opposing locking mechanisms are generally identical and, for purposes of simplicity of description, only the one shown will be described herein. Locking mechanism 30 is comprised of a ball bearing 32 received in a bore 34 having a mouth 36 which is of a diameter slightly less than the diameter of the ball bearing. A spring, which is not shown, typically biases ball bearing 32 to seat against mouth 36 so that a portion of the ball extends outwardly from the blade into a recess 38 defined by upright structure 26 of the handle which opposes mouth 36. When the blade is in the operative position, the ball bearings are intended to resiliently hold the blade in position during use of the laryngoscope.
While the laryngoscope, as depicted in FIGS. 1 and 2, is generally satisfactory for its intended purpose, there is a particular aspect of the instrument as shown and described above which is improved upon by the present invention, as will be discussed below.
The particular problem with the prior art laryngoscope described above resides in the fact that the blade does not positively lock to the handle when the blade is mounted on the handle in its operative position. Opposing locking mechanisms 30 do provide a measure of retention, but it is of a resilient nature such that sufficient applied force will disengage the detents and allow the handle to move to an inoperative position adjacent the blade. This problem is particularly troublesome during withdrawal from the patient of the laryngoscope instrument of the type shown in FIG. 1 due to the fact that, as the instrument is withdrawn from the patient, considerable force must be applied to the handle in a direction which tends to disengage the locking mechanisms. Since a health care professional is generally concerned with many other aspects of the procedure being undertaken, such as, for example, separation of an intubated tube from the laryngoscope, it is undesirable for the handle to move to an inoperative position during such a procedure.
As will be seen hereinafter, the present invention provides a laryngoscope including means for positively locking the blade to the handle while the blade in its operative position.